WASHINGTON (CNN) --The U.S. Air Force Tuesday tested the biggest conventional bomb in the military's arsenal, dropping the new 21,000-pound device on a test site at Eglin Air Force Base, Florida, U.S. officials said.

The Pentagon hopes the test will pave the way for use of the bomb -- should there be a war in Iraq -- against critical targets on the surface and underground.

The new Massive Ordnance Air Blast, or MOAB, was dropped from a military transport plane over a test site at Eglin, 60 miles east of Pensacola, Florida, just after 2 p.m.

It was the final test of the new Massive Ordnance Air Blast, or MOAB, and the first to use actual explosives. Two previously undisclosed tests, one in February and one on Friday, were inert.

The Air Force released video of the Tuesday's test, which showed the bomb falling through the sky and bursting into a massive fireball upon impact. A cloud of smoke then rose hundreds of feet into the sky.

The video was released in hopes of placing additional pressure on the Iraqi military, officials said.

"The goal is to have the pressure be so great that Saddam Hussein cooperates," Defense Secretary Donald Rumsfeld told reporters. "Short of that -- an unwillingness to cooperate -- the goal is to have the capabilities of the coalition so clear and so obvious that there is an enormous disincentive for the Iraqi military to fight against the coalition."

The National Earthquake Information Center said it found no seismic activity as a result of the explosion, as some in the military had indicated might occur. A 10,000-foot cloud had been expected and local residents had been warned of possible loud noise.

Kathy Fite, a waitress at the International House of Pancakes in Fort Walton Beach, about 20 miles from the test site, said she heard the explosion, but it did not rattle the restaurant's windows or shake the ground.

She described the explosion as loud, but "not real loud." Fite said the blast was comparable to the sound of warships that sometimes test fire in the area.

Pentagon officials said they were examining results of the test to determine whether it worked as designed.

MOAB, privately known in military circles as "the mother of all bombs," has been under development since late last year. The bomb carries 18,000 pounds of tritonal explosives, which have an indefinite shelf life. It replaces the Vietnam-era "Daisy Cutter," a 15,000-pound bomb with 12,600 pounds of the less-powerful GSX explosives.

As originally conceived, the MOAB was to be used against large formations of troops and equipment or hardened above-ground bunkers. The target set has also been expanded to include deeply buried targets.

But military officials tell CNN that the MOAB is mainly conceived as a weapon employed for "psychological operations." Military officials say they hope the MOAB will create such a huge blast that it will rattle Iraq troops and pressure them into surrendering or not even fighting. Officials suggest perhaps the Iraqis might even mistake a MOAB blast for a nuclear detonation.

The MOAB is deployed on a pallet from a C-130 aircraft. It initially has a parachute, but as it deploys, the Inertial Navigation System and Global Positioning System take over. The bomb also has wings and grid fins for guidance.